Stop at the next safe work boundary and release all queued/active runs.
Wake the driver loop (e.g. after admissionHeld flips back to false).
Read-only native preparation borrows a boundary of the live execution group. Model mutation still requires the gateway's exclusive drain.
Optional
Submit a request; resolves when its row finishes (EOS, stop, or length).
Stop at the next safe work boundary and release all queued/active runs.